netdev - [PATCH net-next] net: altera_tse: fix init sequence to avoid races with register

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Date: Sun, 11 Jun 2023 12:40:19 +0200
From: Maxime Chevallier <maxime.chevallier@...tlin.com>
To: davem@...emloft.net
Cc: Maxime Chevallier <maxime.chevallier@...tlin.com>,
	netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	thomas.petazzoni@...tlin.com,
	Andrew Lunn <andrew@...n.ch>,
	Jakub Kicinski <kuba@...nel.org>,
	Eric Dumazet <edumazet@...gle.com>,
	Paolo Abeni <pabeni@...hat.com>,
	Russell King <linux@...linux.org.uk>,
	linux-arm-kernel@...ts.infradead.org,
	Simon Horman <simon.horman@...igine.com>,
	alexis.lothore@...tlin.com
Subject: [PATCH net-next] net: altera_tse: fix init sequence to avoid races with register_netdev

As reported here[1], the init sequence in altera_tse can be racy should
any operation on the registered netdev happen after netdev registration
but before phylink initialization.

Fix the registering order to avoid such races by making register_netdev
the last step of the probing sequence.

[1]: https://lore.kernel.org/netdev/ZH9XK5yEGyoDMIs%2F@shell.armlinux.org.uk/

Fixes: fef2998203e1 ("net: altera: tse: convert to phylink")
Signed-off-by: Maxime Chevallier <maxime.chevallier@...tlin.com>
---
This patch targets net-next as it fixes a commit that is in net-next
too.

 drivers/net/ethernet/altera/altera_tse_main.c | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/drivers/net/ethernet/altera/altera_tse_main.c b/drivers/net/ethernet/altera/altera_tse_main.c
index 2e15800e5310..54f1b5ad84ce 100644
--- a/drivers/net/ethernet/altera/altera_tse_main.c
+++ b/drivers/net/ethernet/altera/altera_tse_main.c
@@ -1395,12 +1395,6 @@ static int altera_tse_probe(struct platform_device *pdev)
 	spin_lock_init(&priv->rxdma_irq_lock);
 
 	netif_carrier_off(ndev);
-	ret = register_netdev(ndev);
-	if (ret) {
-		dev_err(&pdev->dev, "failed to register TSE net device\n");
-		goto err_register_netdev;
-	}
-
 	platform_set_drvdata(pdev, ndev);
 
 	priv->revision = ioread32(&priv->mac_dev->megacore_revision);
@@ -1449,12 +1443,16 @@ static int altera_tse_probe(struct platform_device *pdev)
 		goto err_init_phylink;
 	}
 
+	ret = register_netdev(ndev);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to register TSE net device\n");
+		return ret;
+	}
+
 	return 0;
 err_init_phylink:
 	lynx_pcs_destroy(priv->pcs);
 err_init_pcs:
-	unregister_netdev(ndev);
-err_register_netdev:
 	netif_napi_del(&priv->napi);
 	altera_tse_mdio_destroy(ndev);
 err_free_netdev:
-- 
2.40.1